Using wafer geometry to improve scanner correction effectiveness for overlay control

Abstract

Systems and methods for providing improved scanner corrections are disclosed. Scanner corrections provided in accordance with the present disclosure may be referred to as wafer geometry aware scanner corrections. More specifically, wafer geometry and/or wafer shape signature information are utilized to improve scanner corrections. By removing the wafer geometry as one of the error sources that may affect the overlay accuracy, better scanner corrections can be obtained because one less contributing factor needs to be modeled.

What is claimed is: 
     
       1. A method for providing scanner corrections, comprising:
 providing a plurality of wafer geometry groups; 
 identifying a particular wafer geometry group out of the plurality of wafer geometry groups that best matches wafer geometry of a given wafer; and 
 applying at least one scanner correction value associated with the particular wafer geometry group to the given wafer. 
 
     
     
       2. The method of  claim 1 , wherein providing a plurality of wafer geometry groups further comprises:
 collecting wafer geometry data from a reference set of wafers; and 
 classifying the reference set of wafers into the plurality of wafer geometry groups based on the wafer geometry data. 
 
     
     
       3. The method of  claim 2 , wherein providing a plurality of wafer geometry groups further comprises:
 calculating at least one scanner correction value independently for each of the plurality of wafer geometry groups. 
 
     
     
       4. The method of  claim 1 , wherein the wafer geometry includes at least one higher order shape characterization. 
     
     
       5. The method of  claim 1 , wherein the at least one scanner correction value includes at least one higher order correction value. 
     
     
       6. The method of  claim 1 , wherein identifying a particular wafer geometry group out of the plurality of wafer geometry groups that best matches wafer geometry of a given wafer further comprises:
 comparing at least one of: cross-correlations, sigma of difference pairs, and a combination of cross-correlations and sigma of difference pairs between the given wafer and each of the plurality of wafer geometry groups to identify a best matching wafer geometry. 
 
     
     
       7. The method of  claim 1 , wherein the method is adapted for providing wafer overlay monitor and control. 
     
     
       8. The method of  claim 1 , further comprising:
 applying a shape correction to the given wafer prior to applying the at least one scanner correction value. 
 
     
     
       9. The method of  claim 8 , wherein applying the shape correction to the given wafer further comprises:
 collecting raw overlay data of the given wafer to obtain a raw overlay signature of the given wafer; 
 obtaining a shape signature of the given wafer based on the wafer geometry of the given wafer; and 
 removing the shape signature of the given wafer from the raw overlay signature of the given wafer. 
 
     
     
       10. The method of  claim 9 , wherein a correction per exposure technique is utilized to remove the shape signature of the given wafer from the raw overlay signature of the given wafer. 
     
     
       11. A system, comprising:
 a measurement device configured to collect wafer geometry data from a given wafer; and 
 an analyzer in communication with the measurement device, the analyzer configured to:
 provide a plurality of wafer geometry groups; 
 identify a particular wafer geometry group out of the plurality of wafer geometry groups that best matches wafer geometry of the given wafer; and 
 apply at least one scanner correction value associated with the particular wafer geometry group to the given wafer. 
 
 
     
     
       12. The system of  claim 11 , wherein the measurement device is further configured to collect wafer geometry data from a reference set of wafers, and wherein the analyzer is further configured to classify the reference set of wafers into the plurality of wafer geometry groups based on the wafer geometry data. 
     
     
       13. The system of  claim 12 , wherein the analyzer is further configured to calculate at least one scanner correction value independently for each of the plurality of wafer geometry groups. 
     
     
       14. The system of  claim 11 , wherein the wafer geometry includes at least one higher order shape characterization. 
     
     
       15. The system of  claim 11 , wherein the at least one scanner correction value includes at least one higher order correction value. 
     
     
       16. The system of  claim 11 , wherein the analyzer is configured to compare at least one of: cross-correlations, sigma of difference pairs, and a combination of cross-correlations and sigma of difference pairs between the given wafer and each of the plurality of wafer geometry groups to identify a best matching wafer geometry. 
     
     
       17. The system of  claim 11 , wherein the system is adapted to provide wafer overlay monitor and control. 
     
     
       18. The system of  claim 11 , wherein the analyzer is further configured to apply a shape correction to the given wafer prior to apply the at least one scanner correction value. 
     
     
       19. The system of  claim 18 , wherein the analyzer is configured to:
 collect raw overlay data of the given wafer to obtain a raw overlay signature of the given wafer; 
 obtain a shape signature of the given wafer based on the wafer geometry of the given wafer; and 
 remove the shape signature of the given wafer from the raw overlay signature of the given wafer to apply the shape correction to the given wafer prior to apply the at least one scanner correction value. 
 
     
     
       20. The system of  claim 19 , wherein the analyzer utilizes a correction per exposure technique to remove the shape signature of the given wafer from the raw overlay signature of the given wafer.